Devices and methods for port-access multivessel coronary artery bypass surgery

ABSTRACT

Surgical methods and instruments are disclosed for performing port-access or closed-chest coronary artery bypass (CABG) surgery in multivessel coronary artery disease. In contrast to standard open-chest CABG surgery, which requires a median sternotomy or other gross thoracotomy to expose the patient&#39;s heart, port-access CABG surgery is performed through small incisions or access ports made through the intercostal spaces between the patient&#39;s ribs, resulting in greatly reduced pain and morbidity to the patient. In situ arterial bypass grafts, such as the internal mammary arteries and/or the right gastroepiploic artery, are prepared for grafting by thoracoscopic or laparoscopic takedown techniques. Free grafts, such as a saphenous vein graft or a free arterial graft, can be used to augment the in situ arterial grafts. The graft vessels are anastomosed to the coronary arteries under direct visualization through a cardioscopic microscope inserted through an intercostal access port. Retraction instruments are provided to manipulate the heart within the closed chest of the patient to expose each of the coronary arteries for visualization and anastomosis. Disclosed are a tunneler and an articulated tunneling grasper for rerouting the graft vessels, and a finger-like retractor, a suction cup retractor, a snare retractor and a loop retractor for manipulating the heart. Also disclosed is a port-access topical cooling device for improving myocardial protection during the port-access CABG procedure. An alternate surgical approach using an anterior mediastinotomy is also described.

[0001] This application is a continuation-in-part of copending U.S.patent application Ser. No. 08/281,891, filed Jul. 28, 1994, whichitself is a continuation-in-part of copending U.S. patent applicationSer. No. 08/023,778, filed Feb. 22, 1993. The complete disclosures ofthese related U.S. patent applications are hereby incorporated herein byreference for all purposes.

FIELD OF THE INVENTION

[0002] The present invention relates generally to devices and methodsfor performing thoracoscopic cardiac procedures. More particularly, thepresent invention relates to devices and methods for performing coronaryartery bypass graft (CABG) surgery for multivessel coronary arterydisease through port-access or closed-chest thoracoscopic methods.

BACKGROUND OF THE INVENTION

[0003] Coronary artery disease remains the leading cause of morbidityand mortality in Western societies. Coronary artery disease ismanifested in a number of ways. For example, disease of the coronaryarteries can lead to insufficient blood flow resulting in the discomfortand risks of angina and ischemia. In severe cases, acute blockage ofcoronary blood flow can result in myocardial infarction, leading toimmediate death or damage to the myocardial tissue.

[0004] A number of approaches have been developed for treating coronaryartery disease. In less severe cases, it is often sufficient to treatthe symptoms with pharmaceuticals and lifestyle modification to lessenthe underlying causes of disease. In more severe cases, the coronaryblockage(s) can often be treated endovascularly using techniques such asballoon angioplasty, atherectomy, laser ablation, stents, hot tipprobes, and the like.

[0005] In cases where pharmaceutical treatment and/or endovascularapproaches have failed or are likely to fail, it is often necessary toperform a coronary artery bypass graft procedure using open surgicaltechniques. Such techniques require that the patient's sternum be openedand the chest be spread apart to provide access to the heart. A sourceof arterial blood is then connected to a coronary artery downstream froman occlusion while the patient is maintained under cardioplegia and issupported by cardiopulmonary bypass. The source of blood is often theleft or right internal mammary artery, and the target coronary arterycan be the left anterior descending artery, circumflex artery, rightcoronary artery or any one of their branches which might be narrowed oroccluded.

[0006] While very effective in many cases. the use of open surgery toperform coronary artery bypass grafting is highly traumatic to thepatient. The procedure requires immediate postoperative care in anintensive care unit, a total period of hospitalization of seven to tendays, and a recovery period that can be as long as six to eight weeks.

[0007] It would therefore be desirable to provide other, less traumaticmethods and techniques for performing coronary artery bypass grafting.It would be particularly desirable if such techniques did not requireopening of the patient's sternum, and might be even more desirable ifsuch techniques could be performed using thoracoscopic methods. Suchthoracoscopic methods could decrease morbidity and mortality, cost, andrecovery time when compared to conventional open surgical coronarybypass procedures. In addition, such methods could be even moreefficacious than open-surgical bypass procedures.

[0008] Treatment of multivessel coronary artery disease involvesrerouting multiple conduits to supply blood to the blocked coronaryarteries downstream of the blockages. Typical conduits used for CABGsurgery in multivessel disease include arterial conduits, such as theleft internal mammary artery (LIMA), the right internal mammary artery(RIMA) or the right gastroepiploic artery (RGEA), or venous conduitssuch as the greater saphenous vein (GSV) or the lesser saphenous vein(LSV). Often a combination of these and other conduits is necessary toachieve complete revascularization of the obstructed coronary arteries.Open-chest approaches to treatment of multivessel coronary arterydisease are described in Alternative Bypass Conduits and Methods forSurgical Coronary Revascularization, by Grooters and Nishida, FuturaPublishing Company, Inc., Armonk, N.Y., 1994. Other references forstandard open-chest methods of coronary artery bypass surgery include:Cardiac Surgery, by Kirklin and Barratt Boyes, John Wiley & Sons, Inc.New York, 1993 (2nd Ed.), and Rob and Smith's Operative Surgery, CardiacSurgery. The C V Mosby Co. St Louis, Mo., 1983 (4th Ed.).

[0009] A major challenge of thoracoscopic CABG surgery in multivesseldisease is the ability to visualize and anastomose all of the coronaryarteries through a limited number of access ports in order to minimizethe trauma to the patient. This is made more difficult because many ofpreferred anastomosis sites on the branches of the right coronary arteryand the circumflex artery are on the posterior aspect of the heart andtherefore are difficult to access and to visualize with the heart insitu. Operating on the heart in situ would require separate access portsfor the left coronary artery and each of the right coronary artery andthe circumflex artery. Making this many access ports in the patient'schest would undermine the atraumatic aspect of the thoracoscopicapproach. In open-chest CABG surgery, this problem is solved bywithdrawing the heart from the pericardial sac and manipulating it toexpose the arteries on the posterior aspect. No instruments currentlyexist for manipulating the heart within the closed chest of the patient,making it difficult to duplicate the close-chest procedure withthoracoscopic techniques. Devices and methods are therefore necessaryfor manipulating the heart within the patient's closed chest to exposeeach of the coronary arteries for visualization and anastomosis.

[0010] The additional length of time required for performing multipleanastomoses in multivessel CABG surgery also poses difficulties in termsof myocardial preservation during the lengthy procedure. In openprocedures additional myocardial protection can be provided by topicalhypothermia of the heart to reduce oxygen demand by the myocardium. Theinstruments and systems currently available for topical hypothermia incardiac surgery are not suited for thoracoscopic techniques. New devicesand methods are therefore necessary for cooling the heart within thepatient's closed chest to extend myocardial preservation during themultivessel CABG procedure.

SUMMARY OF THE INVENTION

[0011] The present invention describes devices and methods forperforming port-access or closed-chest CABG surgery to treat multivesselcoronary artery disease. All of the major steps of the port-access CABGprocedure are performed through small percutaneous access ports to avoidthe necessity of a median sternotomy or other gross thoracotomy, asrequired in prior open-chest approaches. The methods of the presentinvention include the steps of dissecting one or more conduit vessels.preferably arterial conduits, from their native locations, rerouting theconduit vessels to the heart and grafting the conduit vessels onto theblocked coronary arteries downstream of the blockages.

[0012] Generally, the step of dissecting the conduit vessels from theirnative locations or the “takedown” is performed through small accessports using endoscopic visualization. In the case of a LIMA or RIMAtakedown, the access ports are made into the patient's thoracic cavitythrough the intercostal spaces and visualization is achieved using aflexible thoracoscope. Rerouting the LIMA involves redirecting thedistal end of the LIMA to the desired anastomosis site. The RIMA may bererouted anteriorly of the heart or it may be tunneled through thetransverse sinus to reach the desired anastomosis site. In the case ofan RGEA takedown, the access ports are made into the patient's abdomenand visualization is achieved using a laparoscope. Rerouting the RGEAinvolves tunneling the distal end of the RGEA through a hole in thediaphragm to reach the desired anastomosis site on the heart. If venousgrafts, such as the GSV, or other free grafts are used in place of or inaddition to the arterial conduits, then the takedown or harvesting ofthe graft is performed by open or closed surgical techniques asappropriate and the graft is rerouted to the patient's chest foranastomosis.

[0013] Specialized instruments for facilitating the takedown andrerouting steps are provided as part of the present invention. Oneinstrument provided is a thoracoscopic tunneler for directing anarterial conduit through the transverse sinus or other tunneling path.One embodiment of a tunneler has an elongated shaft with a curved, rigiddistal end with a hole through the distal tip for passing a tape orsilastic tube through the transverse sinus to retract theaorto-pulmonary trunk to facilitate passage of the arterial conduitthrough the transverse sinus. Another embodiment of a tunneler has anelongated shaft with an articulated distal end with a grasper forreaching through the transverse sinus to grasp the arterial conduit anddraw it through the transverse sinus to the desired anastomosis site.The two tunneling instruments may be used separately or in combination.In addition, a specialized thoracoscopic electrosurgical device may beprovided to facilitate takedown of the arterial conduits. A suitablethoracoscopic electrosurgical device for this application is describedin co-owned, copending patent application. Ser. No. 08/336.359, filedNov. 8, 1994. the entire disclosure of which is hereby incorporated byreference.

[0014] The step of grafting the conduit vessels onto the heart isaccomplished under direct visualization using a cardioscopic microscopeinserted through a visualization port into the patient's thoracic cavitymade through an intercostal space in the anterior wall of the chest.Additional surgical instruments are inserted through auxiliary portsinto the patient's thoracic cavity to perform the anastomosis of theconduit vessels to the coronary arteries. The devices and methods of thepresent invention are devised to minimize the trauma to the patient bymaking it possible to visualize and access all aspects of the heart froma single centrally located visualization port by manipulating the heartwithin the patient's closed chest with instruments inserted through theauxiliary access ports or through the takedown ports which remain fromthe takedown step. Generally, the distal end of each conduit vessel orgraft is anastomosed to a coronary artery downstream of a blockage.Additionally, the conduit vessels may be sequentially grafted to morethan one coronary artery or branch to form a “skip graft”. If freegrafts are used an additional step of creating a proximal anastomosismust be performed. The proximal end of the graft may be anastomosed tothe ascending aorta or to another of the conduit vessels to form aY-graft. The step of making the proximal anastomosis may be performedbefore or after the distal anastomosis, depending on the preferences ofthe surgeon.

[0015] Specialized instruments are provided for manipulating the heartwithin the closed chest of the patient to rotate the desired anastomosissite into the visual field of the cardioscopic microscope. Thespecialized instruments include retractors which can manipulate theheart from outside of the body through one or more of the access ports.One embodiment of a retractor has an elongated shaft with a handle atthe proximal end and a curved, finger-like manipulator at the distalend. The curved, finger-like manipulator may be covered with anabsorbent and/or frictional material to improve its effectiveness atretracting, rotating and manipulating the heart. Another embodiment of aretractor has an elongated tubular shaft with a suction cup-shapedmanipulator at the distal end. A vacuum is applied between the suctioncup manipulator and the surface of the heart to grip the heart. Thedistal surface of the suction cup manipulator may have a textured orhighly frictional surface to increase the grip on the surface of theheart, especially in a direction tangential to the surface. Theretractor can thus be used to retract or rotate the heart in anydirection to expose the desired anastomosis site.

[0016] Another aspect of the present invention is to provide myocardialprotection to the heart for the duration of the surgical procedure. Afirst component of the myocardial protection is to provide a means forestablishing cardiopulmonary bypass (CPB) without the need forperforming a thoracotomy or other grossly invasive procedure. Onenoninvasive method of establishing CPB involves the insertion of anendoaortic occlusion catheter into the ascending aorta through apercutaneous puncture into a peripheral artery. An inflatable occlusionballoon on the distal end of the catheter is used to partition theascending aorta between the coronary ostia and the brachiocephalicartery to isolate the heart and coronary arteries from the remainder ofthe arterial system while it is supported on cardiopulmonary bypass.Cardioplegic solution to temporarily stop the heart from beating may beinfused into the coronary arteries through the catheter and/or through aretroperfusion catheter percutaneously inserted in the coronary sinus.This method is more completely described in co-owned, copending patentapplication. Ser. No. 08/281,891, filed Jul. 28, 1994.

[0017] Another relatively noninvasive method of establishing CPBinvolves using a thoracoscopic cross-clamp to isolate the heart andcoronary arteries from the remainder of the arterial system while it issupported on cardiopulmonary bypass. The thoracoscopic cross-clamp isinserted into the patient's thoracic cavity through an access port.Co-owned, copending patent application, Ser. No. 08/173,899, filed Dec.27, 1993, the entire disclosure of which is hereby incorporated byreference, describes a specialized thoracoscopic cross-clamp suitableuse with the present invention and a method of its use for isolating theheart and establishing CPB.

[0018] A second component of the myocardial protection is to provide ameans for applying topical hypothermia to the heart to reduce oxygendemand by the myocardium while the patient is on cardiopulmonary bypassand particularly while the heart is under cardioplegic arrest. Aspecialized topical hypothermia system that can be appliedthoracoscopically through small access ports into the chest is providedas part of the present invention. The topical hypothermia systemincludes a flexible heat exchanger which is collapsible to fit throughan access cannula inserted into an intercostal space. The heat exchangeris deployable to an expanded position once it is inside of the thoraciccavity. The heat exchanger is placed in thermal contact with the heartand a cooling fluid is circulated from outside the body through coolingpassages within the heat exchanger. The temperature of the heart can belowered for the duration of the procedure to reduce oxygen demand. Theheat exchanger can also be used for warming the heart at the end of theprocedure by circulating a warm fluid through the cooling passages.

BRIEF DESCRIPTION OF THE DRAWINGS

[0019]FIG. 1 shows the takedown step for using the left internal mammaryartery (LIMA) or the right internal mammary artery (RIMA) as an arterialbypass conduit.

[0020]FIG. 2 shows the tunneling of the RIMA through the transversesinus (TS).

[0021]FIG. 3 shows the laparoscopic takedown of the right gastroepiploicartery (RGEA).

[0022]FIG. 4 shows the tunneling of the RGEA through the diaphragm intothe thoracic cavity.

[0023]FIG. 5 shows the operative ports for performing the anastomosis ofthe arterial conduits onto the coronary arteries.

[0024]FIG. 6 shows a position of the heart for performing an anastomosisto the right coronary artery (RCA) or the posterior descending (PDA)branch.

[0025]FIG. 7 shows an alternate position of the heart for performing ananastomosis to the RCA or the PDA.

[0026]FIG. 8 shows the position of the heart for performing ananastomosis to the circumflex artery (Cx) or the obtuse marginal (OM)branches.

[0027]FIG. 9 shows the position of the heart for performing ananastomosis to the left anterior descending artery (LAD).

[0028] FIGS. 10-15 show the step-by-step sequence of creating anend-to-side anastomosis.

[0029]FIG. 16 shows the heart of the patient with multiple completedbypass grafts.

[0030] FIGS. 17-18 show the step-by-step sequence of creating aside-to-side anastomosis.

[0031]FIG. 19 shows the heart of the patient with sequential anastomoseson a “skip graft”.

[0032]FIG. 20 shows the heart of the patient with a saphenous veinbypass graft.

[0033]FIG. 21 shows the heart of the patient with a Y-graft.

[0034]FIG. 22 shows a first embodiment of a tunneler for retracting thepulmonary trunk away from the transverse sinus.

[0035]FIG. 23 shows a schematic diagram of a patient's heart with thetunneler of FIG. 22 in use.

[0036]FIG. 24 shows a second embodiment of a tunneler having anarticulating distal end.

[0037]FIG. 25 is an enlarged detail drawing of the multilink articulatoron the distal end of the articulating tunneler of FIG. 24.

[0038]FIG. 26 shows an embodiment of the articulating tunneler of FIG.24 with a grasper on the distal end for grasping the RIMA and drawing itthrough the transverse sinus.

[0039]FIG. 27 shows a schematic diagram of a patient's heart with thearticulating tunneler of FIG. 26 in use.

[0040]FIG. 28 shows a first embodiment of a heart retractor with afinger-like manipulator on the distal end.

[0041]FIG. 29 shows an alternate embodiment of a heart retractor havinga finger-like manipulator combined with a suction irrigation lumen.

[0042]FIG. 30A shows a die-cutting pattern for the covering material tocover the finger-like manipulator of FIG. 28. FIG. 30B shows an enlargeddetail drawing of the die-cutting pattern of FIG. 30A.

[0043]FIG. 31 shows a cross section of a patient showing the heartretractor of FIG. 28 in use.

[0044]FIG. 32 shows the heart retractor of FIG. 28 fixed to theoperating table to stabilize the heart.

[0045]FIG. 33A shows a side view of a second embodiment of a heartretractor having a suction cup-shaped manipulator on the distal end.FIG. 33B shows a longitudinal cross section of the distal end of theheart retractor of FIG. 33A. FIG. 33C shows a distal end view of theheart retractor of FIG. 33A.

[0046]FIG. 34 shows a cross section of a patient showing the heartretractor of FIG. 33 in use.

[0047]FIG. 35 shows the heart retractor of FIG. 33 used to rotate theheart to expose the Cx and the OM branches on the left aspect of theheart.

[0048]FIG. 36 shows a third embodiment of a heart retractor with aflexible snare on the distal end for manipulating the heart.

[0049]FIG. 37 shows the heart retractor of FIG. 36 in a predeployedposition for insertion through an access cannula.

[0050]FIG. 38 shows a cross section of a patient showing the heartretractor of FIG. 36 in use.

[0051]FIG. 39 shows a fourth embodiment of a heart retractor formanipulating the heart in a predeployed position for insertion throughan access cannula.

[0052]FIG. 40 shows the heart retractor of FIG. 39 in a deployedposition for manipulating the heart.

[0053]FIG. 41 shows a cross section of a patient showing the heartretractor of FIG. 39 in use.

[0054]FIG. 42 shows a first embodiment of a topical hypothermia devicefor cooling a patients heart to improve myocardial protection duringport-access cardiac surgery.

[0055]FIG. 43 shows the topical hypothermia device of FIG. 42 in apredeployed position for insertion through an access port.

[0056]FIG. 44 shows the topical hypothermia device of FIG. 42 in adeployed position.

[0057]FIG. 45 shows the topical hypothermia device of FIG. 42 in usewithin the chest of a patient.

[0058]FIG. 46 shows a second embodiment of a topical hypothermia devicefor cooling a patients heart to improve myocardial protection duringport-access cardiac surgery.

[0059]FIG. 47 shows the topical hypothermia device of FIG. 46 in adeployed position.

[0060]FIG. 48 shows a first embodiment of an anterior mediastinotomyapproach for performing closed-chest multivessel CABG surgery.

[0061]FIG. 49 shows a second embodiment of an anterior mediastinotomyapproach for performing closed-chest multivessel CABG surgery.

[0062]FIG. 50 shows a top view of a fiberoptically illuminated ovalaccess cannula.

[0063]FIG. 51 shows a side view of the fiberoptically illuminated ovalaccess cannula of FIG. 50.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0064] The Surgical Method

[0065]FIG. 1 is a schematic view of a patient's thorax illustrating thetakedown step of the port-access CABG procedure. The takedown stepshould be performed while the patient is under general anesthesia, butbefore the patient has been placed on cardiopulmonary bypass. If theLIMA is to be used as an arterial bypass conduit, a series of accessports are created on the left lateral side of the patient's chest, asshown in FIG. 1. The access ports are created by incising the skin witha scalpel between two of the patient's ribs, then an access cannula 112with a trocar is pushed through the intercostal space. Preferably, aself-anchoring access cannula 112 with a 10-12 mm internal diameter isused for the takedown ports. The placement of the access ports is highlyvariable, depending on the preferences of the surgeon and the anatomy ofthe patient which is assessed fluoroscopically before the operation toverify the preferred locations.

[0066] In one preferred embodiment of the method, to allow the takedownof the LIMA, a first access port 103 is placed in the third intercostalspace I3 on the left lateral side of the patient's chest, a secondaccess port 104 is placed in the fifth intercostal space I5, and a thirdaccess port 105 is placed in the sixth intercostal space I6 in aslightly more anterior position from the first two. Meanwhile, the leftand right bronchi are individually intubated just below the bifurcationof the trachea so that the lungs can be individually ventilated. Theleft lung is deflated to provide clearance between the lung and the leftanterior wall of the thoracic cavity while the patient is ventilatedthrough the right lung. A flexible thoracoscope 111 is inserted throughone of the access ports, such as the third access port 105 as shown inFIG. 1. The distal end of the flexible thoracoscope 111 can be directedtoward the anterior wall of the thoracic cavity just to the left of thesternum S to view the LIMA. Elongated instruments, such as anelectrosurgical device 110 and a grasper 109, are inserted through theremaining ports 104, 103 to dissect the LIMA from the anterior wall ofthe chest. The LIMA is dissected with an attached pedicle. Side branchesof the LIMA are ligated with ligating clips, applied with athoracoscopic clip applier, as the LIMA is dissected from thesurrounding tissue. A length of LIMA of 15-30 cm is dissected from thewall to provide enough length to reach the chosen anastomosis site. Whena sufficient length of LIMA has been dissected, two ligating clips areplaced side-by-side near the distal end of the LIMA and the vessel istransected between them.

[0067] If the patient's lungs are ventilated by high frequency “jet”ventilation, then the RIMA can also be harvested frQm the access ports103, 104, 105 on the left side of the patient's chest, provided thepatient's chest has ample space between the heart and the anterior wallof the thoracic cavity. To do this, both lungs are partially deflatedwhile continuing to ventilate, thereby allowing clearance to reach theRIMA from the left side of the chest. After dissecting the mediastinalpleura, the distal end of the thoracoscope 111 is directed toward theanterior wall of the thoracic cavity just to the right of the sternum Sto view the RIMA and the RIMA is taken down in a similar fashion to theLIMA.

[0068] If conventional ventilation is used, sufficient ventilationcannot be achieved with both lungs partially deflated, so this option isnot available. In this case, access ports 106. 107, 108 symmetrical tothe left hand ports are placed in the lateral right side of the chest,typically in the third I3, fifth I5 and sixth I6 intercostal spaces. Theright lung is deflated to provide clearance between the lung and theanterior wall of the thoracic cavity while the left lung is ventilated.The flexible thoracoscope 111 is inserted through one of the accessports and instruments, such as the electrosurgical device 110, graspers109 and/or a clip applier, are inserted through the remaining ports todissect the RIMA from the anterior chest wall. A length of 15-30 cm ofRIMA with an attached pedicle is dissected from the chest wall toprovide enough length to reach the chosen anastomosis site. When asufficient length of RIMA has been dissected, two ligating clips areplaced side-by-side near the distal end of the RIMA and the vessel istransected between them.

[0069] When rerouting the RIMA to the anastomosis site, two paths arepossible. The currently preferred path is through the transverse sinusTS which is a natural passage behind the aorta A and the pulmonaryartery P leading from the right side of the heart H to the left side.The RIMA is tunneled through the transverse sinus TS by passing aninstrument, such as the articulated tunneling grasper 150 describedbelow in relation to FIG. 24, through the transverse sinus TS anddrawing the distal end of the RIMA back through the transverse sinus TS,as shown in FIG. 2. (nota bene: The patient's chest has been shown withthe ribs R cut away in FIG. 2, and subsequent figures, solely for thepurposes of illustration. An important feature of the port-accesssurgical method of the present invention is that the ribs and thesternum remain intact throughout the surgical procedure.) To facilitatethe tunneling operation, a tunneler 140, such as the one described belowin relation to FIG. 22, can be used to retract the pulmonary trunk P toallow easier passage of the RIMA through the transverse sinus TS. Thesecond path for rerouting the RIMA is across the anterior side of theheart H. This routing of the RIMA is not currently preferred by mostsurgeons in open-chest CABG operations because the oscillating sawcommonly used for doing the sternotomy in redo CABG operations can causedamage to the RIMA if it is placed in an anterior position. However, itis interesting to note that redo CABG will not require the oscillatingsaw to open the sternotomy if the original CABG operation was done withport-access techniques that do not require a sternotomy. The lesstraumatic reciprocating saw, commonly used in first time CABG surgery,can be used if a redo operation is necessary because it will be thepatient's first sternotomy. As the techniques for port-access CABGsurgery advance, the simpler anterior route for the RIMA is likely tobecome the preferred path.

[0070] If a third arterial conduit is required for completerevascularization of the heart or if either of the internal mammaryarteries is not available, then the right gastroepiploic artery (RGEA)is the next choice. FIG. 3 shows the laparoscopic takedown step for theRGEA. A first laparoscopic access port 113 is placed above the umbilicusand a second laparoscopic access port 114 is placed below the diaphragm.A third 115 and fourth 116 access ports may be placed in the left andright side of the abdomen as shown for insertion of instruments. TheRGEA is dissected from the greater curvature of the stomach ST using anelectrosurgical device. Ligating clips are placed on branches of theRGEA running toward the omentum. Branches 117 running toward the stomachare preferably ligated with suture. A length of 15-30 cm of RGEA with anattached pedicle is dissected from the stomach to provide enough lengthto reach the chosen anastomosis site. When a sufficient length of RGEAhas been dissected, two ligating clips 118 are placed side-by-side nearthe distal end of the RGEA and the vessel is transected between them.

[0071] A hole 119 is made through the diaphragm D in an appropriateplace for reaching the desired anastomosis site using an electrosurgicaldevice. The distal end of the RGEA is tunneled upward through thediaphragm D as shown in FIG. 4. In FIG. 4, the rerouted RGEA is shownbeing anastomosed to the PDA on a heart H which has been retracted bythe methods described below to expose the posterior aspect of the heart.

[0072] If a venous graft, such as the greater saphenous vein (GSV), isneeded, a venous takedown procedure can be performed by known techniquesto provide a venous conduit. After harvesting, the vein can be preparedfor use as a graft outside of the body and inserted into the thoraciccavity through one of the access ports at the appropriate time in thegrafting step of the procedure.

[0073] Simultaneously with the takedown step or steps just described,the patient can be prepared for cardiopulmonary bypass by cannulatingthe femoral artery and the femoral vein using surgical cutdowns or thepercutaneous Seldinger technique. Additionally, an endoaortic occlusioncatheter may be positioned in the ascending aorta according to themethods described in co-owned, copending patent application Ser. No.08/281,891, filed Jul. 28, 1994. According to the methods describedtherein, an elongated endoaortic occlusion catheter is introduced into aperipheral artery, such as the femoral artery and advanced into theascending aorta. When it is time to establish CPB before the graftingstep described below, an occlusion balloon on the distal end of thecatheter is inflated to occlude the aortic lumen between the coronaryostia and the brachiocephalic artery. Once the balloon is inflated acardioplegic agent can be infused through a lumen in the catheter intothe aortic root and into the coronary arteries to induce cardiac arrest.Alternatively, a thoracoscopic cross-clamp may be introduced through oneof the access ports according to the methods described in co-owned,copending patent application Ser. No. 08/173,899, filed Dec. 27, 1993,the entire disclosure of which is hereby incorporated by reference.According to the methods described therein, an elongated thoracoscopiccross-clamp is introduced through one of the access ports and, at theappropriate time, clamped around the ascending aorta to occlude theaortic lumen. A cardioplegic agent may be introduced antegrade into theaortic root or retrograde through the coronary sinus to induce cardiacarrest. This is in preparation for the grafting step of the method ofthe present mention which follows.

[0074] At this point in the procedure the pericardium is opened toexpose the heart as completely as possible. Using thoracoscopicobservation, grasping instruments and cutting instruments, such asknives, scissors and/or an electrosurgical device are inserted throughthe takedown ports 103, 104, 105 and a vertical slit beginning at ornear the aortic reflection and extending to the apex of the heart ismade in the pericardium. Thoracoscopic bipolar electrosurgical cuttingscissors, such as model 3803 bipolar scissors from Everest MedicalCorporation. Minneapolis, Minn., have proven to be an effectiveinstrument for performing the pericardiotomy. The pericardium is dividedto expose the surface of the heart H to view.

[0075]FIG. 5 shows the operative ports for performing the anastomosis ofthe arterial conduits onto the coronary arteries. A visualization port120 is placed in the anterior wall of the chest, typically through thefourth intercostal space 14, about 1-3 cm from the sternum S. Theprecise placement of the visualization port 120 is determined by theposition of the heart H within the patient's chest. A probe, such as a22 gauge needle can be inserted percutaneously through the intercostalspace while observing the anterior wall of the thoracic cavity throughthe thoracoscope. When the needle is observed entering the thoraciccavity above the target position, for instance above the LAD when theheart is in its native position, the needle is removed and a trocar isused to create an access port at that position. An access cannula 121with an internal diameter of 10-12 mm is placed in the access port 120and the cardioscopic microscope (not shown) is inserted through thecannula. A cardioscopic microscope, adapted especially for thisport-access CABG procedure is available from Karl Zeiss, GmbH, Germany.The presently preferred configuration uses an OPMI® microscope, modelMDU or CS, with an NC31 microscope stand, an endoscopic adapter and aPort-Access StereoVision Probe. Other types of microscope-based anddirect visualization systems which are particularly well-suited for usein the method of the present invention are disclosed in co-owned,copending patent applications Ser. No. 08/135, 387, filed Oct. 8, 1993,and Ser. No. 08/227,366, filed Apr. 13, 1994, the complete disclosuresof which are hereby incorporated herein by reference. With themicroscope positioned in the visualization port 120, the left anteriordescending coronary artery (LAD) should be within the field of view ofthe microscope.

[0076] A number of instrument ports 122 are placed about 3-5 cm from thevisualization port to allow proper angulation of the instruments intothe field of view of the microscope. Typically, two ports 122 are placednear the sternum S in the third I3 and fourth I4 intercostal spaces andtwo more ports 122 are placed to the left of the visualization port inthe third I3 and fifth I5 intercostal spaces. An access cannula 123 withan internal diameter of 5 mm is placed in each of the instrument ports122.

[0077] Next the graft vessels, whether arterial or venous conduits, mustbe prepared for anastomosis. Preferably, the distal ends of the graftvessels are prepared outside of the body by passing the distal end ofthe graft out through one of the access ports. This simplifies theprocedure because the end of the graft can be prepared under directvisualization with magnifying surgical loupes and because standardsurgical instruments can be used for preparing the graft rather thanthoracoscopic instruments. The LIMA or RIMA can be passed out throughone of the thoracic access ports (e.g. access port 103 or 106 in FIG. 1)before rerouting or tunneling the vessel. The RGEA can be passed outthrough one of the abdominal access ports (e.g. access port 113 or 114in FIG. 3) before tunneling the RGEA through the diaphragm D. If thegraft vessel is too short to reach the exterior of the body through oneof the access ports, the following graft vessel preparation procedurecan also be carried out within the thoracic cavity using thoracoscopicinstruments and techniques. Prior to preparing the graft vessel, theblood flow into the vessel must be stopped by placing an atraumaticclamp (e.g. 124 in FIG. 4) on the upstream end of the vessel. Anatraumatic thoracoscopic bulldog clamp especially suited for this stepof the procedure is described in co-owned. copending patent applicationSer. No. 08/265,477. filed Jun. 24, 1994.

[0078] The graft vessel should be prepared by first determining theappropriate length of the conduit in order to reach the desiredanastomosis site. The distal end of the graft vessel should then beskeletonized by stripping the pedicle away from the artery for 5-10 mm.The distal end of the artery is transected to remove the ligating clip118 that was previously applied. If desired. Papavarin may be injectedinto the lumen of the artery to dilate it and reverse any arterialspasm. Depending on the technique preferred by the surgeon, the distalend of the graft vessel can be slit longitudinally to create a cobrahead for the anastomosis. Once prepared, the graft vessel is reinsertedinto the thoracic cavity through the access port.

[0079] When performing multiple anastomoses, it is preferable to do themost difficult or most difficult to reach anastomosis first. Forexample, any anastomosis to the RCA or the PDA should be performed firstsince the most retraction of the heart is necessary. Following that, anyanastomosis to the Cx or the OM branches should be performed. Finally,any anastomosis to the LAD can be performed last. The RIMA, RGEA or avein graft may be used for anastomosis to the RCA or the PDA which areon the posterior aspect of the heart. Typically. the LIMA, RIMA or avein graft is used when a graft is needed for the Cx or the OM branchesbecause of their location on the left aspect of the heart. The LIMA, orthe RIMA if the LIMA has already been used for the Cx, may be used foranastomosis to the LAD which is on the anterior aspect of the heart.Because the manifestations of coronary artery disease are highlyvariable, the extent of the disease should be assessed fluoroscopicallybeforehand and the anastomosis sites and the best use of the availableconduits strategized carefully. The procedures for anastomosing to eachof the major anastomosis sites will now be described. These procedurescan be performed in combination to achieve complete revascularization ofthe heart.

[0080]FIG. 6 shows a first position of the heart H for performing ananastomosis to the right coronary artery (RCA) or the posteriordescending (PDA) branch. The heart H is manipulated from outside of thebody using instruments inserted through the instrument ports 122 or thetakedown ports 103, 104, 105 in the patient's chest. Using the heartretractor devices described below in connection with FIGS. 26 and 27 orany suitable means for manipulating the heart from outside of the body,the heart H is rotated approximately 180 degrees to the left of thepatient to position the RCA and/or PDA under the microscope in thevisualization port 120. With the heart H stabilized in this position,the distal extremity of the conduit vessel is approximated to the chosenanastomosis site and an end-to-side anastomosis is performed. The likelygraft vessels for the RCA and the PDA, which include the RIMA and theRGEA, are shown in phantom lines in FIG. 6. After completion of theanastomosis, the heart H is rotated back to its native position or tothe desired position for the next anastomosis.

[0081]FIG. 7 shows an alternate position of the heart H for performingthe anastomosis to the RCA or the PDA. In this variation of theprocedure, the heart H is rotated approximately 180 degrees about anaxis 125 which is at an approximately 45 degree angle to the sagittalaxis of the body. Flipped upward this way, the RCA and the PDA arepositioned under the microscope in the visualization port 120. With theheart H stabilized in this position, the distal extremity of the conduitvessel is approximated to the chosen anastomosis site and an end-to-sideanastomosis is performed. The likely graft vessels for the RCA and thePDA, which include the RIMA and the RGEA, are shown in phantom lines inFIG. 7. After completion of the anastomosis, the heart H is rotated backto its native position or to the desired position for the nextanastomosis.

[0082]FIG. 8 shows the position of the heart H for performing ananastomosis to the circumflex artery (Cx) or the obtuse marginal (OM)branches. In order to access the Cx or the OM branches which are on theleft aspect of the heart or the left posterior aspect of the heart, theheart H is rotated toward the right by 45 to 90 degrees using retractioninstruments inserted through the access ports (e.g. 103, 104, 105). Inthis position the Cx and/or the OM branches will be positioned under themicroscope in the visualization port 120. With the heart H stabilized inthis position, the distal extremity of the conduit vessel isapproximated to the chosen anastomosis site and an end-to-sideanastomosis is performed. The likely graft vessels for the Cx and the OMbranches, which include the LIMA and the RIMA, are shown in phantomlines in FIG. 8. After completion of the anastomosis. the heart H isrotated back to its native position or to the desired position for thenext anastomosis.

[0083] With the more difficult to reach anastomoses completed and theheart H back in its native position, as shown in FIG. 9 the anastomosisto the LAD can now be completed. With the heart H in its nativeposition, the LAD will be positioned under the microscope in thevisualization port 120. With the heart H stabilized in this position,the distal extremity of the conduit vessel is approximated to the chosenanastomosis site and an end-to-side anastomosis is performed. The likelygraft vessels for the LAD, which include the LIMA and the RIMA, areshown in phantom lines in FIG. 9.

[0084] Alternatively to manipulating the heart within the closed chestto expose the different aspects, a second visualization port 126 andinstrument ports 127 can be opened on the right side of the chest. asshown in phantom lines in FIG. 5, to access the right coronary arteryRCA directly. In another alternative approach, right side access portsmay be used alone if only the right coronary artery RCA and/or theobtuse marginal OM branches are to be revascularized or if the patient'sanatomy favors a right side approach for multivessel revascularization.

[0085] FIGS. 10-15 show the step-by-step sequence of creating anend-to-side anastomosis. Referring now to FIG. 10, an incision 95 ismade in the wall of the coronary artery CA, where the incision hasdimensions selected to match those of the distal end of the internalmammary artery graft IMA. The incision 95 is made by first piercing thearterial wall using the tip of a scalpel (not illustrated). Scissors 96are then introduced through the penetration and used to axially extendthe penetration, as illustrated at 97 in FIG. 11.

[0086] The internal mammary artery IMA can be joined to the extendedincision 97 in the coronary artery CA by a variety of techniques,including suturing, laser welding, microstapling, and the like. In acurrently preferred embodiment of the method of the present invention,it is preferred to use a continuous suturing technique as illustrated inFIGS. 10-15. A length of suture 98 has needles 100 at either end, whichare manipulated using forceps 102 to join the distal end 101 of theinternal mammary artery IMA graft to the opening created by the incision97 in the coronary artery CA, as shown in FIGS. 11-15. The instrumentdesigns presently preferred for performing the coronary anastomosis aredescribed in copending application Ser. No. 08/194,946, filed Feb. 11,1994, the entire disclosure of which is hereby incorporated herein byreference. Alternatively, an interrupted suture technique for theanastomosis can be used, as described in Rob and Smith's OperativeSurgery, Cardiac Surgery for open-chest CABG surgery.

[0087] The presently preferred suture for port-access CABG surgery is adouble-armed suture of 8-10 cm length which was specially developed forthis procedure. The suture 98 has a first needle 100 on one end and asecond needle 100 on the other end. Preferably, the needles 100 are ⅜circle curved hardened stainless steel needles with tapered points. Theneedles 100 are preferably attached to the suture 98 by crimping.Alternatively, the needles 100 may be adhesively bonded to be suture 98.The preferred suture material 98 is a multifilament, expanded PTFEsuture material with a size between 8-0 and 6-0 USP, preferably 7-0 USP.Suitable suture material of this type is available from W. L. Gore,Corporation under the tradename Goretex®. A contrasting color which ishighly visible within the thoracic cavity, such as black, blue or white,is preferred for the suture material.

[0088] The configuration of this suture is especially advantageous foruse in the port-access surgical CABG procedure. The suture can beinserted into the thoracic cavity through an access port and manipulatedusing thoracoscopic needle drivers to sew the anastomosis and to tie thesuture within the thoracic cavity. Standard sutures, which are normallymuch longer, are very difficult to manipulate within the closed chest,especially when tying the suture using thoracoscopic instruments. Theshort length of the suture allows the knots in the suture to be pulledtight within the confines of the thoracic cavity while grasping theneedles with the needle drivers. The multifilament, expanded PTFE suturematerial is much easier to handle and tie within the confines of thethoracic cavity than monofilament suture material which is generallystiffer and harder to handle. Additionally, the multifilament, expandedPTFE suture material has more resistance to damage than monofilamentwhen it is grasped directly by the needle drivers, as shown in FIGS. 11,14 and 15.

[0089]FIG. 16 shows the heart H of a patient after completion of a totalrevascularization for multivessel coronary artery disease usingport-access techniques. Three bypass grafts have been made, using theLIMA as a bypass to one of the OM branches of the Cx, the RIMA as abypass to the LAD, tunneled via the transverse sinus TS, and the RGEA asa bypass to the PDA, tunneled through the diaphragm.

[0090] A sequential grafting technique or “skip grafting” is useful forachieving total revascularization when the number of significantcoronary artery stenoses exceeds the number of available graft conduits.Sequential grafts are created by making a side-to-side anastomosis witha first coronary artery at an intermediate point on the graft vessel,then an end-to-side anastomosis between the distal end of the graftvessel and a second coronary artery. FIGS. 17-18 show the step-by-stepsequence of creating a side-to-side anastomosis between a graft vessel Gand a coronary artery CA. The side-to-side anastomosis is fashioned in adiamond-shaped manner, placing the graft vessel arteriotomy 128 at rightangles to the coronary arteriotomy 129. Small arteriotomies, 3-4 mm inlength, are used and six to eight continuous stitches 130 are placedthrough the coronary artery CA and the graft vessel G. An interruptedsuture technique can also be used. FIG. 19 shows the heart H of apatient with a completed sequential graft. The LIMA has been firstgrafted to the diagonal branch LD of the left anterior descendingcoronary artery using a side-to-side anastomosis 131, then grafted tothe LAD with an end-to-side anastomosis 132.

[0091] Free grafts using either arterial conduits or venous conduits canbe used to augment the in situ arterial grafts. Generally, the proximalend of a free grafts is anastomosed to the ascending aorta A to providean arterial blood source and the distal end of the graft is anastomosedto one of the coronary arteries. A common source of free grafts is thegreater saphenous vein. Other conduits used as free grafts include thelesser saphenous vein, the LIMA, the RIMA, the inferior epigastricartery, the splenic artery, the subclavian artery, and others. FIG. 20shows the heart H of a patient with a saphenous vein bypass graft SVG tothe LAD. The proximal anastomosis 133 can be created using suturetechniques similar to those described in connection with FIGS. 10-15above with the exception that a thoracoscopic tissue punch would be usedto create an aortotomy after the initial incision with a scalpel.Alternatively, the proximal anastomosis 133 can be created using ananastomosis staple device, such as those described in co-owned,copending patent application Ser. No. 08/394,333, filed Feb. 24, 1995,the entire disclosure of which is hereby incorporated by reference.

[0092] Free grafts can be combined with in situ grafts or other freegrafts to create composite bypass grafts to help achieve totalrevascularization for multivessel disease. For example, a free graft canbe anastomosed to the distal end of an in situ graft like the LIMA orRIMA when there is insufficient length of the graft after takedown.Alternatively, a Y-graft can be created as an alternative to thesequential grafts described above. FIG. 21 shows the heart H of apatient with a Y-graft. The Y-graft was created by joining the proximalend of a free right internal mammary artery graft F-RIMA to anintermediate point on a LIMA in situ graft with an end-to-sideanastomosis 134, then grafting the distal end of the RIMA to the Cx withan end-to-side anastomosis 135 and grafting the distal end of the LIMAto the LAD with an end-to-side anastomosis 136. Other conduits includingarterial and venous grafts can be combined in various combinations tocreate composite grafts.

[0093] Instrument Descriptions

[0094] FIGS. 22-47 show an armamentarium of instruments for facilitatingthe port-access multivessel CABG procedure. FIG. 22 shows a firstembodiment of a tunneler 140 for retracting the pulmonary artery awayfrom the ascending aorta to facilitate tunneling the RIMA through thetransverse sinus TS. The tunneler 140 has an elongated shaft 141 ofsufficient length to reach the great vessels of the heart from thetakedown ports in the left lateral side of the chest, typically 15-30 cmin overall length. There is a handle 142 on the proximal end of theshaft 141. The distal portion 143 of the shaft is curved to facilitatepassing the tunneler 140 through the transverse sinus TS from the leftside of the heart. The distal tip 144 of the shaft is rounded to make itatraumatic. There is a hole 145 through the shaft 141 near the distaltip 144 of the tunneler 140. In use. a silastic tape 146 or elastomerictube is threaded through the hole 145 and the distal end of the tunneleris inserted through one of the takedown ports (e.g. 103 in FIG. 23).Under thoracoscope observation, the curved distal portion 143 isinserted behind the pulmonary artery P and the ascending aorta A andpassed through the transverse sinus TS to the right side of the heart,as shown in FIG. 23. When the distal tip 144 of the tunneler 140 emergeson the right side of the heart H, a grasper is inserted through one ofthe access ports, typically one of the takedown ports on the leftlateral side of the chest, to grasp one side of the tape 146. Theretractor 140 is withdrawn and the ends of the tape 146 are passed outthrough the access ports, preferably one of the takedown ports locatedat the third or fourth intercostal space, and tension is placed on thetape 140 to retract the main pulmonary artery P and the ascending aortaA (the aorto-pulmonary trunk), thereby widening the transverse sinus TS.With the pulmonary artery P and the ascending aorta A retracted, agrasping instrument, such as the articulated tunneling grasper 150 ofFIG. 26, can more easily be reached through the transverse sinus TS.

[0095] A basic embodiment of the articulated tunneling grasper 150 isshown in FIG. 24. The articulated tunneling grasper 150 has an elongatedtubular shaft 151 with a handle 152 on the proximal end. A multilinkarticulator 153 is attached to the distal end of the shaft 151. Themultilink articulator 153 is shown in detail in FIG. 25. The multilinkarticulator 153 has a head 154 which attaches to the distal end of theshaft 151. Two links 155, 156 are pivotally attached to the head 154.The first link 155 is a straight link. The proximal end of the firstlink 155 is pivotally attached to the head 154. The second link 156 isan L-shaped link with a long leg 157 that is approximately the samelength as the first link 155, and a short leg 158 extendingperpendicular from the proximal end of the long leg 157. The second link156 is pivotally attached to the head 154 at the proximal end of thelong leg 157. An actuator rod 159 that passes through the tubular shaft151 connects the end of the short leg 158 with a sliding actuator button160 on the handle 152. The first link 155 and the second link 156 crossone another and their distal ends are pivotally attached to a third link161. The third link 161 is an L-shaped link with a long leg 162extending distally, and a short leg 163 extending perpendicular from theproximal end of the long leg 162. When the actuator rod 159 is in itsneutral position the multilink articulator 153 is in a relativelystraight position, as shown in FIG. 24 by solid lines 153. When theactuator rod 159 is moved distally with respect to the head 154, itpivots the second link 156 clockwise, as shown in FIG. 24 by phantomlines 153′. The relative motion of the first 155 and second links 156,in turn, pivots the third link 161 clockwise, as shown. When theactuator rod 159 is moved proximally with respect to the head 154, itpivots the second link 156 counterclockwise, as shown in FIG. 24 byphantom lines 153′. The relative motion of the first 155 and secondlinks 156, in turn, pivots the third link 161 counterclockwise. Thedistal end of the multilink articulator 153 can thus pivot approximately90 degrees in either direction.

[0096] Various end effectors can be attached to the distal end of themultilink articulator 153 for performing different tasks. The possibleend effectors include a simple hole 164, as shown in FIG. 24, forplacing a tape through the transverse sinus TS for retracting theaorto-pulmonary trunk, or a heart retraction device, such as a suctionretractor or finger retractor, as discussed in more detail below, or agrasping mechanism, such as a cable-actuated grasper.

[0097] In one particularly preferred embodiment, shown in FIG. 26, acable-actuated grasper 165 is mounted on the distal end of the multilinkarticulator 153 shown in FIG. 24. The grasper 165 has a first 166 andsecond 167 jaw with grasping surfaces on the facing surfaces of the jaws166, 167. At least one of the jaws 166. 167, and preferably both jaws.are pivotally attached to the distal end of the third link 166, 167. Anactuator cable (not shown) extends from a control button 168 on thehandle 152, through the tubular shaft, and to a linkage connected to thegrasper jaws 166, 167. The jaws of the grasper 166, 167 can be actuatedto open and close using the control button 168.

[0098] In use, the articulated tunneling grasper 150 is inserted throughone of the takedown ports 103, 104, 105 in a straight position. Thedistal end of the grasper 165 is inserted behind the pulmonary artery Pand the ascending aorta A, and through the transverse sinus TS, as shownin FIG. 27. The multilink articulator 153 is actuated to assume anappropriate curve to pass easily through the transverse sinus TS. Oncethe distal end of the grasper 165 emerges from the transverse sinus TSon the right side of the heart H, as shown in FIG. 27, the multilinkactuator 153 can be used to manipulate the grasper 165 closer to theRIMA. Another grasper may be inserted through another access port toassist with handling the RIMA to the articulated tunneling grasper 150.The grasper 165 is opened, then closed to grasp the pedicle of the RIMAso as not to damage the vessel. The articulated tunneling grasper 150,with the RIMA in its grasp, is withdrawn through the transverse sinus TSto the left side of the heart H. The RIMA has thus been tunneled throughthe transverse sinus TS from the right side of the heart to the leftside, as discussed above in relation to FIG. 2.

[0099] Tunneling the RIMA through the transverse sinus TS from the rightside of the heart to the left side is the currently preferred path forrerouting the RIMA for attachment to the Cx or the OM branches.Alternatively, the RIMA can be routed across the anterior side of theheart using the articulated tunneler or another thoracoscopic graspingdevice. When rerouting a graft vessel, particularly when tunnelingthrough a space such as the transverse sinus TS, it is important toavoid twisting or kinking the graft vessel. One way to avoid twistingthe vessel is to mark a line along the vessel which can serve as anindicator of whether the vessel is straight. For instance, the vesselcan be marked by drawing a line along the vessel or on the pedicle witha surgical marker containing a nontoxic ink, such as methylene blue. Thevessel is preferably marked before takedown to assure that the vessel isin a straight condition when it is marked. Alternatively, the clips orsutures that are used to ligate side branches of the vessel duringtakedown can be used as markers to determine if the graft vessel isstraight when it is rerouted.

[0100]FIG. 28 shows a first embodiment of a heart retractor 170 with afinger-like manipulator 171 on the distal end for rotating the heartwithin the closed chest of the patient to expose each of the coronaryarteries to be anastomosed. The retractor 170 has an elongated shaft 172of approximately 15-30 cm with a handle 173 on the proximal end of theshaft. The distal end of the retractor shaft is curved to create afinger-like manipulator 171. The curved manipulator 171 has a radius ofcurvature in one preferred embodiment of approximately 4.5 cm. Theradius of curvature in other embodiment can range from 3.5-6 cm. Thecurvature of the finger-like manipulator 171 subtends an arc ofapproximately 90 to 180 degrees. The finger-like manipulator 171 has anouter diameter of approximately 5-10 mm. The finger-like manipulator 171is preferably molded of a rigid plastic, such as ABS or nylon.Alternatively, the finger-like manipulator 171 can be made of metal,such as stainless steel. In one particular alternative embodiment, thefinger-like manipulator 171 is made of annealed 316 stainless steelwhich is malleable so that it can be manually bent to the desiredcurvature. The exterior of the finger-like manipulator 171 is coveredwith an absorbent and/or high friction material 174 to assist ingrasping and manipulating the heart. The covering 174 of the finger-likemanipulator 174 extends to the very distal end 175 of the manipulator171 and covers the rounded distal tip 175. The preferred material 174for covering the finger-like manipulator 171 is a nonwoven polyesterfabric, embossed with an open mesh pattern. The nonwoven polyester givesthe covering absorbancy, while the open mesh pattern improves thefriction of the surface. A fabric with a self-sticking adhesive surfaceis preferred for convenience in assembling the retractor. The currentlypreferred material for the covering 174 of the finger-like manipulator171 is a 2.4 oz. nonwoven, embossed polyester medical tape with Wetstickm adhesive available from Avery Dennison, Specialty Tape Division,Painesville, Ohio.

[0101] Alternate materials for the covering 174 of the finger-likemanipulator 171 include nonembossed, nonwoven fabrics, such as polyestersurgical felt. While the absorbancy of these materials is quiteacceptable, the friction of the smooth, nonembossed fabric is less thanfor embossed materials. Examples of acceptable materials in thiscategory include Fastsorb 820 and Exsorbx 400 available from BerkshireCorp, Great Barrington, Mass. or Surgical Felt 6077 or 6079 availablefrom BARD, Vascular Surgery Division, Haverhill, Mass. Other materialssuitable for covering the finger-like manipulator 171 include wovenmaterials and knit materials made of polyester, cotton or other fibers.These materials also tend to have a lower coefficient of friction forgripping tissue. Another alternate material for the covering of thefinger-like manipulator 171 is a composite material, including a firstlayer of a highly absorbent material, like surgical felt, and a secondlayer of mesh-like material to increasing the coefficient of frictionfor gripping the surface of the heart.

[0102] The covering material 174 is preferably die cut in a pattern thateasily conforms to the shape of the finger-like manipulator 171. FIG. 30shows a die-cutting pattern 176 for the covering material 174 to cover afinger-like manipulator 171 having a radius of curvature of 4.5 cm whichsubtends 180 degrees of arc, and an outer diameter of 8 mm, such as theone shown in FIG. 28. FIG. 30B shows an enlarged detail drawing of thedie-cutting pattern 176 of FIG. 30A. The self-adhesive covering material174 is cut to this pattern 176 and adhesively bonded to the exterior ofthe finger-like manipulator 171.

[0103] The absorbancy, combined with the texture of the covering 174,gives the retractor 170 a good frictional grip on the surface of theheart. Keeping the interface between the retractor surface and thesurface of the heart dry is important for maintaining a good frictionalgrip. Another preferred embodiment of the retractor 170, shown in FIG.29, combines suction irrigation with the retractor to augment theabsorbancy of the covering material 174. In this embodiment. a suctionlumen 177 extends through the shaft 172 of the retractor 170 and throughthe finger-like manipulator 171. A series of suction holes 178 connectthe suction lumen with the surface of the finger-like manipulator 171 onthe inner curve of the distal end. A constant or intermittent suctionthrough the holes 178 will keep the covering material 174 dry to improvethe frictional grip on the surface of the heart.

[0104] In use, the retractor 170 is typically inserted into the thoraciccavity through one of the takedown ports 103, 104, 105 on the leftlateral side of the chest. The curved finger-like manipulator 171 of theretractor 170 is hooked around the apex of the heart H, as shown in FIG.31. The retractor 170 can be used to rotate or translate the position ofthe heart H within the closed chest. For example, the retractor 170 canbe used to roll the heart H toward the right side of the patient toexpose the Cx or the OM branches on the left aspect of the heart to themicroscope in the visualization port 120. This position of the heart His shown in FIG. 7. The retractor 170 can also be used to lift the apexof the heart and flip the heart 180 degrees to expose the RCA or PDA onthe posterior aspect of the heart H to view. This position of the heartH is shown in FIG. 9.

[0105] The retractor 170 can be fixed to the operating table 180 tostabilize the heart H in the desired position, as shown in FIG. 32. Apositioning device 182, such as those available from Omni-Tract SurgicalDiv., Minneapolis, Minn. or Mediflex Medical Products, Islandia. N.Y.,is attached to the operating table 180 and bent to the correct positionand locked in place. A clamp 181 on the distal end of the positioningdevice 182 is attached to the proximal end of the retractor 180 to holdit in place and maintain the position of the heart H during the courseof the grafting step.

[0106]FIG. 33A shows a side view of an embodiment of a suction heartretractor 190 for manipulating the heart within the closed chest of thepatient. The retractor 190 has an elongated tubular shaft 191 having asuction cup-shaped manipulator 192 on the distal end. The suctioncup-shaped manipulator 192 may be mounted straight on the shaft 191 orit may be mounted at an angle to the shaft 191. In one particularlypreferred embodiment, there is a 45 degree bend 193 near the distal endof the shaft 191 so that the suction cup-shaped manipulator 192 ismounted at a 45 degree angle to the proximal shaft 191. In eitherembodiment, the suction cup-shaped manipulator 192 is preferablyflexibly mounted to the distal end of the shaft 191. A vacuum lumen 194extends through the tubular shaft from the proximal end to the distalend. The distal end of the vacuum lumen 194 is in fluid communicationwith the interior 195 of the suction cup-shaped manipulator 192. Theproximal end of the vacuum lumen 194 is adapted for attachment to avacuum source. A fitting for connecting to the vacuum source, such as abarb fitting or luer fitting, may be attached to the proximal end of thetubular shaft 191, or a flexible extension tube 196 may be attached tothe proximal end of the shaft 191 with a fitting at the far end of theextension tube 196.

[0107] The shaft 191 of the retractor 190 is preferably made of a rigidmaterial that will support the forces required for manipulating theheart without significant deformation. Acceptable materials for theretractor shaft include stainless steel and liquid crystal polymer. Tofacilitate forming an angled or curved shaft, a mineral filled liquidcrystal polymer (e.g. calcium carbonate) is preferred. This material canbe heat formed at 350 to 400 degrees F.

[0108]FIG. 33B shows a longitudinal cross section of the distal end ofthe heart retractor 190 of FIG. 33A, and FIG. 33C shows a distal endview of the heart retractor of FIG. 33A. The suction cup-shapedmanipulator 192 has an external diameter of approximately 12 to 50 mmfor a surface area of approximately 110 to 1960 mm². The surface area ofthe suction cup-shaped manipulator 192 allows a firm grip on the surfaceof the heart H when a vacuum is applied to the interior 195 of thesuction cup 192, without causing vacuum damage to the tissue. A valve197 on the shaft 191 of the retractor 190 allows the surgeon to controlthe vacuum to turn it on and off. Preferably, the vacuum should belimited to a maximum of 150 mmHg to avoid tissue damage. The suctioncup-shaped manipulator 192 is made of a soft, flexible elastomericmaterial, such as silicone rubber with a hardness of approximately 40 to80 Shore A durometer. The soft, flexible suction cup-shaped manipulator192 is designed so that when a vacuum is applied within the interior 195of the suction cup 192, the suction cup 192 conforms to the surface ofthe heart H and does not cause deformation of the heart tissue.

[0109] The distal surface 198 of the suction cup-shaped manipulator 192is textured to create a high friction surface. In one particularlypreferred embodiment, the suction cup-shaped manipulator 192 has apattern of bumps 199 on the distal surface 198 and a circular ridge 200around the periphery of the suction cup 192. The bumps 199 in onepreferred embodiment have a height of approximately 1 mm with a 120degree conical end and straight sides. Other geometries for thefriction-increasing bumps 199 include conical, cylindrical orhemispherical, as well as other possible geometries. The circular ridge200 around the periphery has a height of approximately 1-2 mm. Thegeometry and the pattern of the bumps 199 create a reliable frictiongrip on the surface of the heart H under vacuum without causing anydamage to the heart tissue. An alternative embodiment of the retractorhas an absorbent high friction material (not shown) adhesively attachedto or cast into the distal surface of the suction cup-shaped manipulator192 in place of the pattern of bumps. A suitable absorbent high frictionmaterial for this application is a nonwoven polyester fabric embossedwith an open mesh pattern.

[0110] In use, the distal end of the retractor 190 is inserted throughone of the access ports, typically one of the takedown ports 103, 104,105 in the left lateral side of the patient's chest. The soft, flexiblenature of the suction cup-shaped manipulator 192 allows it to be foldedor collapsed as it is pushed through the access port. The retractor 190can be inserted through an access cannula 112 or the cannula 112 can beremoved from the access port 103 to facilitate insertion of the suctioncup-shaped manipulator 192 directly through the access port 103. In onepreferred embodiment of the method, suction cup-shaped manipulator 192is placed on the anterior surface of the heart H near the apex, as shownin FIG. 34, and a vacuum is applied to grip the surface of the heart.From this position, the retractor 192 can be used to rotate the heart Hin either direction. In FIG. 35, the retractor 190 has been used torotate the heart H approximately 90 degrees to the right to expose theCx and the OM branches on the left aspect of the heart to view. Theretractor 190 can also be used to rotate the heart 180 degrees to theleft to expose the RCA and PDA on the posterior aspect of the heart, asin FIG. 8. In an alternative embodiment of the method, the suctioncup-shaped manipulator 192 is placed on the posterior side of the heartnear the apex and a vacuum is applied to grip the surface of the heart.Then, the retractor 190 is used to lift and rotate the heart to flip it180 degrees to expose the RCA and PDA on the posterior aspect of theheart, as in FIG. 7. This retractor 190 can also be fixed to theoperating table to stabilize the heart in the desired position similarlyto the embodiment of FIG. 32.

[0111]FIG. 36 shows a third retraction device 210 for manipulating theheart within a patient's closed chest. The retraction device 210 has anelongated tubular shaft 211. The tubular shaft 211 has a right anglebend 212 at the distal end. A first end 213 of a flexible snare 214 isattached to the shaft 211 at the distal end. The second end of theflexible snare extends through a lumen within the tubular shaft 211 andattaches to a sliding handle 215 at the proximal end. The snare 214 ismade of a flexible wire or band. Preferably, the flexible wire or bandis covered with a soft, flexible friction material to increase thesurface area and to improve the frictional grip on the heart. Suitablematerials for the covering of the snare include soft, flexible polymersor elastomers or absorbent, high-friction fabrics. The flexible wire orband 214 of the snare is preferably made of a highly resilient materialsuch as a superelastic nickel/titanium alloy or a spring temperstainless steel or titanium alloy.

[0112]FIG. 37 shows the heart retractor of FIG. 36 in a predeployedposition for insertion through an access cannula. When the slidinghandle is in a proximal position, the snare 214′ forms a small loop, asshown in FIG. 37, which easily deforms to fit through a 10 mm accesscannula. When the sliding handle 215 is in a distal position, the snare215 forms a large loop 214, as shown in FIG. 36, which is large enoughto encircle the heart H. The wire is preferably preshaped so that thesnare opens up in a loop 214 perpendicular to the axis of the distalsegment 216 of the shaft 211. FIG. 38 shows a cross section of a patientshowing the retraction device 210 inserted into the thoracic cavitythrough one of the access ports 103 with the snare encircling the heartH. From this position, the retractor 210 can be used to manipulate theheart H to a desired position. For example, the retractor 210 can beused to lift and rotate the heart H to flip it 180 degrees to expose theRCA and PDA on the posterior aspect of the heart, as in FIG. 7.

[0113]FIG. 39 shows a fourth retractor device 220 for manipulating theheart within the close chest of a patient in a predeployed position forinsertion through an access cannula. The retractor 220 has an elongatedtubular shaft 221 with a handle 226 on the proximal end. In a preferredembodiment, the distal end 222 of the shaft has an angled portion at anapproximately 0 to 45 degree angle to the proximal portion of the shaft221. A flexible band 223 extends through a lumen within the tubularshaft 221 and extends beyond the distal end of the shaft 221. The distalend of the band 223 is pivotally attached to a distal link 224. Thedistal link 224 is, in turn, pivotally attached to a proximal link 225which, in turn, is pivotally attached to the distal end 222 of thetubular shaft 221. The proximal end of the band 223 is attached to asliding actuator button 227 on the handle 226. When the activator button227 is in a proximal position, the distal portion of the flexible band223 is positioned parallel to and in close proximity to be proximal 225and distal links 224, as shown in FIG. 39. When the activator button 227is in a distal position, the distal portion of the flexible band 223extends from the distal end of the tubular shaft 221 to form a loop 228together with the proximal 225 and distal links 224, as shown in FIG.40. In the illustrative embodiment of FIGS. 39 and 40, the handle 226has a semicircular cassette 229 for storage of the band 223 when theband is in the proximal position. Other embodiments of the retractor 220could have a circular storage cassette or a linear configuration forstoring the retracted band 221. Preferably, the flexible band 223 ismade of a resilient material such as a spring tempered stainless steelor titanium alloy. The proximal 225 and distal links 224 are alsopreferably made of a stainless steel or titanium alloy. The surfaces ofthe flexible band 223 and/or the proximal 225 and distal links 224facing the inside of the loop 229 are preferably covered with a soft,flexible friction material to improve the frictional grip a theretractor on the heart H. Suitable materials for the covering of theloop 228 include soft, flexible polymers or elastomers or absorbent,high-friction fabrics.

[0114] In use, the distal end of the retractor loop 220 is inserted intothe thoracic cavity through one of the access ports 103, typically oneof the takedown ports 103. 104, 105 on the left lateral side of thechest. The actuator button 227 is advanced distally to open the loop 228large enough to encircle the heart H. The loop 22 is passed around theheart H from the apex end and tightened gently around the heart, asshown in FIG. 41. A force limiter can be incorporated into the actuatingmechanism of the retractor 220 to prevent excessive force on the heartH. From this position, the retractor 220 can be used to manipulate theheart H to a desired position. For example, the retractor 220 can beused to lift and rotate the heart to flip it 180 degrees to expose theRCA and PDA on the posterior aspect of the heart, as in FIG. 7.

[0115] FIGS. 42-45 show a topical hypothermia device 230 which can beused to improve myocardial protection during the port-access multivesselCABG procedure. The topical hypothermia device 230 has a flexible heatexchanger 231 which has at least one fluid passage 232 therethrough tocirculate a cooling fluid. The flexible heat exchanger 231 iscollapsible to a predeployed position which can easily fit through anaccess port into the chest of the patient. The flexible heat exchanger231 is attached to the distal end of an elongated tubular shaft 233. Thetubular shaft 233 is preferably made of a rigid material such asstainless steel or a rigid plastic. An inflow lumen 234 extends throughthe tubular shaft 233 and is fluidly connected to the flexible heatexchanger 231. A return lumen 235 extends through the tubular shaft 233parallel to the inflow lumen 234. The inflow lumen 234 and the returnlumen 235 may be formed of extruded plastic tubes which are insertedthrough the tubular shaft 233. Alternatively, the lumens 234, 235 may beformed integrally with the tubular shaft 233 by extrusion. The proximalends of the inflow lumen 234 and the return lumen 235 are adapted forattachment to a circulating pump 236 and a reservoir of cooling fluid237, which is preferably a saline solution.

[0116] In the illustrative embodiment of FIG. 42, the flexible heatexchanger 231 is made from two sheets of flexible plastic which are heatsealed or RF sealed together to form a serpentine cooling path 232through the heat exchanger 231. Preferred materials for manufacturingthe flexible heat exchanger 231 include polyurethane, vinyl,polypropylene, nylon, etc. The flexible heat exchanger 231, in onepreferred embodiment, has a length of 12-18 cm and a width of 7-10 cm.Optionally, the flexible heat exchanger 231 may have a flexible backbone238 which extends from the distal end of the tubular shaft 233 to thedistal edge of the heat exchanger 231. The flexible backbone 238 may bemade from a flexible polymer, elastomer, or a resilient metal wire, suchas spring temper stainless steel or a superelastic nickel/titaniumalloy, or a composite of metal and plastic. The flexible heat exchanger231 is rolled, folded or twisted and placed in an introducer sheath 239in the predeployed position as shown in FIG. 43. Preferably, theintroducer sheath 239 is sized to fit through an access cannula with a10-12 mm internal diameter.

[0117] In use, the topical hypothermia device 230 is prepared in thepredeployed position by first priming the flexible heat exchanger 231 byfilling it with cooling fluid and connecting the proximal end of theinflow lumen 234 and the return lumen 235 to the circulating pump 236and the reservoir of cooling fluid 237. The flexible heat exchanger 231is rolled and covered with the introducer sheath 239. The topicalhypothermia device 230 is inserted through one of the access ports 104in this predeployed position. The distal end of the introducer sheath239 is placed under the heart H and then withdrawn proximally withrespect to the flexible heat exchanger 231, thereby placing the flexibleheat exchanger 231 underneath the heart H. Alternatively, the sheath 239can be withdrawn after the topical hypothermia device 230 is introducedthrough the access port 104 and the flexible heat exchanger 231 placedunder the heart H with the help of the flexible backbone 238. Thecirculating pump 236 is turned on to force cooling fluid into theflexible heat exchanger 231 and through the cooling passage 232. Theflexible heat exchanger 231 inflates with cooling fluid and spreads outunder the heart H to make good thermal contact with the myocardium, asshown in FIG. 45. Preferably. the flexible heat exchanger 231 isconstructed so that it curves to conform to the exterior of the heart Hwhen inflated to the deployed position, as shown in FIG. 44, to create abetter thermal contact with the myocardium. Typically, a cooling fluidat 0-4 degrees Celcius is circulated through the flexible heat exchanger231 with a flow rate of greater than 350 ml/min to rapidly cool theheart.

[0118] In an alternate embodiment of the topical cooling device, theflexible heat exchanger 231 may also be covered with a thermalinsulating material, such as surgical felt, to prevent thermal shock tothe myocardial tissue. Another way to avoid thermal shock to themyocardial tissue is to use a more moderate temperature for the coolingfluid, with better thermal contact and a higher flow rate to rapidlycool the myocardium without the risk of thermal shock.

[0119]FIG. 46 shows an alternate embodiment of the topical coolingdevice 240, which is similar to the embodiment of FIG. 42 except for theconstruction of the flexible heat exchanger 241. In this embodiment, theflexible heat exchanger is in the form of a ring made by heat sealingtwo sheets of plastic together. The cooling fluid enters one side of thering-shaped heat exchanger and follows a serpentine cooling path 242through the heat exchanger 241 around to the other side of the ring. Apreformed, resilient wire loop 248 is attached around the outside of thering-shaped heat exchanger 241 to initialize the shape of the heatexchanger 241 during deployment, as shown in FIG. 47.

[0120] The topical cooling device 230, 240 can be used alone to inducehypothermic cardiac arrest in the patient's heart or the topical coolingdevice 230, 240 can be used in conjunction with cardioplegic arrest toimprove the myocardial protection during the surgical procedure. Inaddition, the topical cooling device 230, 240 can be used to rewarm theheart after the completion of the surgical procedure by circulating warmfluid through the flexible heat exchanger 231, 241. In addition to themultivessel CABG procedure of the present invention, the topical coolingdevice 230, 240 will find utility for improving myocardial protection inany open-chest or closed-chest cardiac surgery.

[0121] Another closely related surgical approach for performingclosed-chest multivessel CABG surgery is through an anteriormediastinotomy, that is, through an incision into the mediastinum, themass of tissues and organs between the lungs that includes the heart.Another term for this surgical approach is a rib-sparing, anteriormini-thoracotomy. There are two ways to perform the anteriormediastinotomy for this approach. The first way is through anintercostal incision 250, 25-50 mm long, in the fourth I4 or fifth I5intercostal space to the left of the sternum S, as shown in FIG. 48. Thesecond way is to create a larger access port 260 by removing either thethird C3, fourth C4 or fifth C5 costal cartilage, preferably on the leftside of the sternum S. When one of the costal cartilages is removed, itcreates an access port 260 approximately 50-60 mm square, as shown inFIG. 49. The access port 260 can be held open using a tissue spreaderfor an access cannula which is oval or square in shape. Actual cuttingor removal of ribs is not necessary. The best position for the port maybe decided by viewing through the lateral IMA takedown ports in thethird or fourth intercostal space and probing with a needle to find thebest position and line of sight for the particular anastomosis site. Itshould be noted that, because the anterior mediastinotomy may cut acrossthe path of the internal mammary artery, it is preferable to make theaccess port after completion of the IMA takedown.

[0122] A tissue spreader or oval cannula 251 for retraction would beuseful to maintain the access channel. Retraction of the ribs should bekept to a minimum in order to reduce the trauma to the patient. Forintroduction without retraction of the ribs, the oval cannula 251 shouldhave interior dimensions of approximately 12 mm width and 25-50 mmlength, and a thin wall of approximately 1 mm thick. For varying degreesof retraction, the width of the oval cannula 251 can be increasedanywhere from 12 mm to 25 mm, which should be sufficient for adequatevisualization and instrument access. Visualization and instrumentinsertion can thus be accomplished through a single elongated accessport, rather than using separate visualization and instrument ports asin the port-access approach described above. Visualization can beaccomplished using a surgical microscope, as described above, or bydirect visualization through the access port 250, 260, with or withoutmagnifying loupes. The cannula 251 should be configured to facilitateretraction of the pedicle through the lumen of the cannula without harmso that the distal end of the graft vessel can be prepared foranastomosis outside of the body under direct visualization. Therefore,the cannula 251 should have no sharp edges that could harm the graftvessel or pedicle. The insertion length of the cannula 251 should beabout 25-50 mm.

[0123] Preferably, illumination means are incorporated into the ovalcannula 251 or into the tissue spreader used to maintain the accesschannel. A light conduction path is incorporated into the wall of theoval cannula 251 or into the blades of the tissue spreader to direct abeam of light distally onto the surgical site. A light source isconnected to the light conduction path. The light source can beintegrated into the device or an external light source may be connectedto the device by an optical cable.

[0124] An exemplary embodiment of an illuminated access device is shownin a top view in FIG. 50 and a side view in FIG. 51. This particularembodiment is an illuminated oval cannula 251, however the followinginventive features can also be incorporated into a blade retractor,tissue spreader, or standard circular access cannula. Optical fibers 252are embedded into the wall of the oval cannula 251. The optical fibersterminate at the distal end of the cannula 251 to direct a beam of lightdistally toward the surgical site. A narrow or diffuse beam of light canbe created depending on the arrangement and the numerical aperture ofthe optical fibers. At the proximal end of the cannula 251, the opticalfibers 252 gather together into an optical connector 253 for connectionto an external light source. In one currently preferred embodiment, amultiplicity of small diameter optical fibers are distributed evenlyabout the periphery of the oval cannula 251. The wall of the ovalcannula 251 can be made of an opaque material to avoid light escapingfrom the optical fibers 252 from interfering with visualization throughthe lumen 254 of the cannula 251. Alternatively, the interior and/orexterior wall of the cannula 251 can be made transparent or translucentto create a diffuse ambient light within or around the cannula 251.

[0125] Anastomosis between the graft vessel and the coronary artery isperformed using instruments inserted through the access port 250, 260.One advantage of this approach is that the access port 250, 260 is largeenough so that the surgeon can insert a finger through the access portor oval cannula 251 to directly palpate the heart, for instance tolocate a stenosis in the coronary artery. It may be advantageous toelevate the heart within the thoracic cavity to facilitate palpation ofthe heart and/or performing the anastomosis. A device similar to thetopical cooling devices 230, 240 of FIGS. 42-47 may be used to elevatethe heart H within the thoracic cavity by inserting it underneath theheart and inflating it, with or without circulating cooling fluid. Thetunneling and retraction devices of FIGS. 22-41 can be used through theaccess port or through the takedown ports to manipulate the heart toexpose different aspects of the heart for visualization and anastomosisof multiple coronary arteries according to the methods described above.Alternatively, a second mediastinal access port 250′, 260′ can be openedon the right side of the chest to access the right coronary arterydirectly. In another alternative approach, a right side mediastinalaccess port 250′, 260′ may be used alone if only the right coronaryartery is to be revascularized or if the patient's anatomy favors aright side approach for multivessel revascularization.

What is claimed is:
 1. A method of cardiac surgery on a heart within achest of a patient, the chest having a sternum and a plurality of ribs,each rib being separated from an adjacent rib by an intercostal space,the method comprising the steps of: making at least one access port intothe chest through an intercostal space, a first aspect of the heartfacing the access port, and a second aspect of the heart facing awayfrom the access port; introducing a retraction instrument through theaccess port; and manipulating the retraction instrument to repositionthe heart within the chest into a retracted position wherein the secondaspect of the heart is facing the access port; wherein the ribs andsternum remain intact during each of said steps.
 2. The method of claim1 wherein the access port is made in a left lateral portion of the chestand wherein the first aspect of the heart comprises a left lateralaspect.
 3. The method of claim 2 wherein the second aspect of the heartcomprises an aspect of the heart selected from a posterior aspect, aright lateral aspect, and an anterior aspect.
 4. The method of claim 1,further comprising the step of: visualizing the heart with avisualization instrument introduced into the chest of the patientthrough a second access port positioned within an intercostal space. 5.The method of claim 1, further comprising the step of: anastomosing avascular graft onto a coronary artery on the heart while the heart is inthe retracted position.
 6. The method of claim 5, wherein theanastomosing step comprises the substep of introducing an anastomosinginstrument into the chest of the patient through an access port withinan intercostal space.
 7. The method of claim 5, wherein the anastomosingstep comprises anastomosing the vascular graft onto a circumflex artery.8. The method of claim 5, wherein the anastomosing step comprisesanastomosing the vascular graft onto a right coronary artery.
 9. Themethod of claim 5 wherein the anastomosing step comprises anastomosingthe vascular graft onto a posterior descending coronary artery.
 10. Themethod of claim 5, wherein the vascular graft is selected from the groupincluding a left internal mammary artery, a right internal mammaryartery, a gastroepiploic artery, a radial artery, a saphenous vein, anda prosthetic vascular graft.
 11. The method of claim 5 furthercomprising the step of: dissecting an internal mammary artery from ananterior wall of the patient's chest; and wherein the anastomosing stepcomprises anastomosing the internal mammary artery onto the coronaryartery.
 12. The method of claim 5, further comprising the step of:anastomosing a second vascular graft onto a second coronary artery usingan anastomosing instrument introduced through an access port within anintercostal space.
 13. The method of claim 12 wherein the secondvascular graft is selected from the group including a left internalmammary artery, a right internal mammary artery, a gastroepiploicartery, a radial artery, a saphenous vein, and a prosthetic vasculargraft.
 14. The method of claim 13 wherein the second coronary arterycomprises a left anterior descending coronary artery.
 15. The method ofclaim 13 wherein the second coronary artery comprises a circumflexartery.
 16. The method of claim 13 wherein the second coronary arterycomprises a right coronary artery.
 17. The method of claim 12 furthercomprising repositioning the heart into a second retracted positionusing said retraction instrument before the step of anastomosing asecond vascular graft.
 18. The method of claim 1 wherein themanipulating step comprises the substep of applying a vacuum between asurface of the retraction instrument and a surface of the heart to gripthe heart with the retraction instrument.
 19. The method of claim 1wherein the manipulating step comprises the substep of lifting the heartwith a rigid finger on the retraction instrument.
 20. The method ofclaim 1 wherein the manipulating step comprises the substeps of placinga flexible loop on the retraction instrument around the heart andtightening the loop.
 21. The method of claim 1 wherein the manipulatingstep comprises rotating the heart.
 22. The method of claim 21 whereinthe heart is rotated about an axis extending longitudinally through theheart from an aortic root generally toward an apex of the heart.
 23. Themethod of claim 21 wherein the heart is rotated about an axis disposedat an acute angle between 0∞ and 90∞ relative to a longtitudinal axisextending from an aortic root toward an apex of the heart.
 24. Themethod of claim 1, further comprising the step of: partitioning anascending aorta of the patient, paralyzing the heart, and maintainingcirculation of oxygenated blood in the patient.
 25. The method of claim24 wherein the partitioning step comprises the substep of introducing anintraluminal occlusion device into a peripheral artery of the patient,transluminally advancing the intraluminal occlusion device into theascending aorta and occluding the ascending aorta between the patient'scoronary ostia and brachiocephalic artery.
 26. The method of claim 1wherein the introducing step comprises the substeps of inserting theretraction instrument through the access port in a predeployed state anddeploying the retraction instrument into a deployed state within thechest of the patient.
 27. The method of claim 26 wherein the retractioninstrument has a profile in the predeployed state which is smaller thanits profile in the deployed state.
 28. The method of claim 27 whereinthe profile in the predeployed state has a diameter of less than about12 mm.
 29. A method of retracting a heart within a chest of a patient,the chest having a sternum and a plurality of ribs, each rib beingseparated from an adjacent rib by an intercostal space. the methodcomprising the steps of: making at least one access port into the chestthrough an intercostal space; introducing a retraction instrumentthrough the access port; applying a vacuum between a surface of theretraction instrument and a surface of the heart to grip the heart withthe retraction instrument; and manipulating the retraction instrument toreposition the heart within the chest of the patient; wherein the ribsand sternum remain intact during each of said steps.
 30. The method ofclaim 29 wherein the step of applying a vacuum comprises applying avacuum through a suction cup attached to the retraction instrument. 31.The method of claim 29 wherein the step of manipulating comprisesengaging the surface of the heart with a textured surface on theretraction instrument to reduce slippage of the retraction instrument onthe surface of the heart.
 32. The method of claim 29 wherein the accessport is positioned so that a first aspect of the heart is facing theaccess port, and a second aspect of the heart is facing away from theaccess port, the step of manipulating comprising repositioning the heartso that the second aspect of the heart is facing the access port. 33.The method of claim 32 wherein the access port is positioned in a leftlateral side of the patient's chest, the first aspect of the heartcomprising a left lateral aspect of the heart.
 34. The method of claim33 wherein the heart is repositioned so that an anterior aspect of theheart is facing the access port.
 35. The method of claim 33 wherein theheart is repositioned so that a posterior aspect of the heart is facingthe access port.
 36. The method of claim 33 further comprisingperforming a surgical procedure on a third aspect of the heart through asecond access port positioned within an intercostal space.
 37. Themethod of claim 35 wherein the surgical procedure comprises anastomosinga vascular graft to a coronary artery on the third aspect of the heart.38. The method of claim 36 wherein the coronary artery is selected fromthe group including the right coronary artery, posterior descendingartery, the left anterior descending coronary artery, and the circumflexartery.
 39. The method of claim 36 wherein the vascular graft isselected from the group including an internal mammary artery, agastroepiploic artery, a radial artery, a saphenous vein, and aprosthetic vascular graft.
 40. The method of claim 36 wherein the secondaccess port is disposed in an anterior side of the patient's chest. 41.The method of claim 29 wherein the step of manipulating comprisesrotating the heart about a longitudinal axis extending from an aorticroot generally toward an apex of the heart.
 42. The method of claim 29wherein the introducing step comprises the substeps of inserting theretraction instrument through the access port in a predeployed state anddeploying the retraction instrument into a deployed state within thechest of the patient.
 43. The method of claim 42 wherein the retractioninstrument has a profile in the predeployed state which is smaller thanits profile in the deployed state.
 44. The method of claim 43 whereinthe profile in the predeployed state has a diameter of less than about12 mm.
 45. A method of cardiac surgery on a heart within a chest of apatient, the chest having a sternum and a plurality of ribs, each ribbeing separated from an adjacent rib by an intercostal space, the methodcomprising the steps of: making at least one access port into the chestthrough an intercostal space; introducing a myocardial cooling devicethrough the access port: and cooling the patient's heart using themyocardial cooling device; wherein the ribs and sternum remain intactduring each of said steps.
 46. The method of claim 45 wherein theintroducing step comprises the substeps of inserting the myocardialcooling device through the access port in a predeployed state anddeploying the myocardial cooling device into a deployed state within thechest of the patient.
 47. The method of claim 46 wherein the myocardialcooling device has a profile in the predeployed state which is smallerthan its profile in the deployed state.
 48. The method of claim 47wherein the profile in the deployed state has a diameter of less thanabout 12 mm.
 49. The method of claim 46 wherein the deploying stepcomprises the substep of inflating the myocardial cooling device with acooling fluid.
 50. The method of claim 46 wherein the deploying stepcomprises the substep of extending the myocardial cooling device fromwithin a sheath.
 51. The method of claim 45 wherein the cooling stepcomprises the substep of positioning the myocardial cooling device inthermal contact with the patient's heart.
 52. The method of claim 45wherein the cooling step comprises the substep of circulating a coolingfluid through the myocardial cooling device.
 53. The method of claim 45,further comprising the step of: anastomosing a vascular graft onto acoronary artery on the patient's heart using an anastomosing instrumentintroduced through an access port within an intercostal space.
 54. Themethod of claim 45, further comprising the step of: introducing aretraction instrument into the patient's chest through an access portwithin an intercostal space; and manipulating the retraction instrumentto reposition the heart within the patient's chest.
 55. A method ofperforming coronary artery bypass graft surgery at a surgical site on aheart within a chest of a patient, the chest having a sternum and aplurality of ribs, each rib being separated from an adjacent rib by anintercostal space, the method comprising the steps of: making first andsecond access ports into the chest through at least one intercostalspace, the surgical site being on an aspect of the heart facing awayfrom the first access port; introducing a retraction instrument throughthe second access port; manipulating the retraction instrument toreposition the heart within the chest into a retracted position whereinthe aspect of the heart containing the surgical site is facing the firstaccess port; and anastomosing a vascular graft to a coronary artery atthe surgical site using an anastomosing instrument introduced throughthe first access port; wherein the ribs and sternum remain intact duringeach of said steps.
 56. The method of claim 55 wherein the second accessport is made in a left lateral portion of the chest.
 57. The method ofclaim 55 wherein the first access port is made in an anterior portion ofthe chest.
 58. The method of claim 57 wherein the aspect of the heart isselected from the group including a posterior aspect, a right lateralaspect, and a left lateral aspect.
 59. The method of claim 55, furthercomprising the step of: visualizing the heart with a visualizationinstrument introduced into the chest of the patient through a thirdaccess port positioned within an intercostal space.
 60. The method ofclaim 55 wherein the anastomosing step comprises anastomosing thevascular graft onto a circumflex artery.
 61. The method of claim 55,wherein the anastomosing step comprises anastomosing the vascular graftonto a right coronary artery.
 62. The method of claim 55 wherein theanastomosing step comprises anastomosing the vascular graft onto aposterior descending coronary artery.
 63. The method of claim 55,wherein the vascular graft is selected from the group including a leftinternal mammary artery, a right internal mammary artery, agastroepiploic artery, a radial artery, a saphenous vein, and aprosthetic vascular graft.
 64. The method of claim 55 further comprisingthe step of: dissecting an internal mammary artery from an anterior wallof the patient's chest; and wherein the anastomosing step comprisesanastomosing the internal mammary artery onto the coronary artery. 65.The method of claim 64 wherein the step of dissecting comprisesdissecting the right internal mammarv artery from an anterior wall ofthe chest using a dissection instrument introduced through an accessport in an intercostal space in a right lateral portion of the chest.66. The method of claim 64 further comprising routing the right internalmammary into a left portion of the chest using a grasping instrumentintroduced through an access port in an intercostal space.
 67. Themethod of claim 66 wherein the right internal mammary artery is routedthrough a transverse epicardial sinus of the patient into the leftportion of the chest.
 68. The method of claim 67 wherein the graspinginstrument is introduced through an access port in a left lateralportion of the chest, further comprising tunneling the graspinginstrument through the transverse epicardial sinus into a right portionof the chest before the step of routing.
 69. The method of claim 55,further comprising the step of: anastomosing the vascular graft onto asecond coronary artery using an anastomosing instrument introducedthrough an access port within an intercostal space.
 70. The method ofclaim 69, wherein the first anastomosing step comprises creating aside-to-side anastomosis between the vascular graft and the coronaryartery and the second anastomosing step comprises creating anend-to-side anastomosis between the vascular graft and the secondcoronary artery.
 71. The method of claim 55, further comprising the stepof: anastomosing a second vascular graft onto a second coronary arteryusing an anastomosing instrument introduced through an access portwithin an intercostal space.
 72. The method of claim 84 wherein thesecond vascular graft is selected from the group including a leftinternal mammary artery, a right internal mammary artery, agastroepiploic artery, a radial artery, a saphenous vein, and aprosthetic vascular graft.
 73. The method of claim 71 wherein the secondcoronary artery is selected from the group including a left anteriordescending coronary artery, a circumflex artery, a right coronaryartery, and a posterior descending coronary artery.
 74. The method ofclaim 71, further comprising the step of: anastomosing the secondvascular graft onto a third coronary artery.
 75. The method of claim 74,wherein the second anastomosing step comprises creating a side-to-sideanastomosis between the second vascular graft and the second coronaryartery and the third anastomosing step comprises creating an end-to-sideanastomosis between the second vascular graft and the third coronaryartery.
 76. The method of claim 55 wherein the manipulating stepcomprises the substep of applying a vacuum between a surface of theretraction instrument and a surface of the heart to grip the heart withthe retraction instrument.
 77. The method of claim 55 wherein themanipulating step comprises the substep of lifting the heart with arigid finger on the retraction instrument.
 78. The method of claim 55wherein the manipulating step comprises the substeps of placing aflexible loop on the retraction instrument around the heart andtightening the loop.
 79. The method of claim 55 wherein the manipulatingstep comprises rotating the heart.
 80. The method of claim 79 whereinthe heart is rotated about an axis extending longitudinally through theheart from an aortic root generally toward an apex of the heart.
 81. Themethod of claim 79 wherein the heart is rotated about an axis disposedat an angle between 0∞ and 90∞ relative to a longtidudinal axisextending from an aortic root toward an apex of the heart.
 82. Themethod of claim 55, further comprising the step of: cooling thepatient's heart with a myocardial cooling device inserted into the chestof the patient through an access port in an intercostal space.
 83. Themethod of claim 55, further comprising the step of: partitioning anascending aorta of the patient, paralyzing the heart, and maintainingcirculation of oxygenated blood in the patient.
 84. The method of claim83 wherein the partitioning step comprises the substep of introducing anintraluminal occlusion device into a peripheral artery of the patient.transluminally advancing the intraluminal occlusion device into theascending aorta and occluding the ascending aorta between the patient'scoronary ostia and brachiocephalic artery.
 85. The method of claim 55wherein the introducing step comprises the substeps of inserting theretraction instrument through the access port in a predeployed state anddeploying the retraction instrument into a deployed state within thechest of the patient.
 86. The method of claim 85 wherein the retractioninstrument has a profile in the predeployed state which is smaller thanits profile in the deployed state.
 87. The method of claim 86 whereinthe profile in the predeployed state has a diameter of less than about12 mm.
 88. The method of claim 55 wherein the step of anastomosingcomprises forming an opening in the coronary artery with a cuttinginstrument introduced through an access port in an intercostal space,and attaching the vascular graft to the coronary artery around theopening.
 89. The method of claim 88 wherein the step of attachingcomprises suturing the vascular graft to the coronary artery using asuturing instrument introduced through an access port in an intercostalspace.
 90. The method of claim 88 wherein the step of attachingcomprises introducing a suture into the chest of the patient through anaccess port in an intercostal space and suturing the vascular graft tothe coronary artery with the suture.
 91. The method of claim 90 whereinthe suture has a first end and a second end, a first needle attached tosaid first end and a second needle attached to said second end, saidsuture having a length of about 8 to 10 centimeters, and wherein thestep of attaching comprises tying the suture within the chest of thepatient using a suturing instrument introduced through an access port inan intercostal space.
 92. The method of claim 55 further comprising thestep of dissecting a gastroepiploic artery within an abdomen of thepatient to create a free end thereof, and routing the free end into thechest, the step of anastomosing comprising anastomosing the free end tothe coronary artery.
 93. The method of claim 92 wherein the step ofdissecting comprises dissecting the gastroepiploic artery using adissection instrument introduced into the abdomen an access cannulapositioned in a wall of the abdomen.
 94. The method of claim 93 whereinthe step of dissecting further comprises visualizing the interior of theabdomen using a scope introduced through an access cannula into theabdomen.
 95. The method of claim 92 wherein the step of routingcomprises creating an opening in a diaphragm of the patient between theabdomen and the chest, and introducing the free end of thegastroepiploic artery through the opening into the chest.
 96. Amyocardial cooling device comprising: a shaft having a proximal end, adistal end, and at least a first lumen therebetween; and an inflatablebladder attached to the distal end of the shaft and having at least onecooling passage therethrough in communication with the first lumen, saidinflatable bladder having a predeployed state and a deployed state.wherein said inflatable bladder is insertable through an access port inan intercostal space when in said predeployed state.
 97. The myocardialcooling device of claim 96 wherein said inflatable bladder is insertablethrough a cannula having an internal diameter of 12 millimeters when insaid predeployed state.
 98. The myocardial cooling device of claim 96further comprising a sheath which covers said inflatable bladder when insaid predeployed state.
 99. The myocardial cooling device of claim 98wherein said inflatable bladder is extended from said sheath when insaid deployed state.
 100. The myocardial cooling device of claim 96wherein said inflatable bladder is inflated with a cooling fluid when insaid deployed state.
 101. The myocardial cooling device of claim 96further comprising a means for circulating a cooling fluid through saidat least one cooling passage.
 102. The myocardial cooling device ofclaim 115 wherein the shaft further comprises a second lumen incommunication with an outlet of said at least one cooling passage,whereby the cooling fluid may be delivered through the first lumen intothe cooling passage, circulated therethrough, and received through thesecond lumen.
 103. The myocardial cooling device of claim 96 wherein theat least one cooling passage comprises a plurality of horizontalpassages interconnected by a series of vertical passages.
 104. Themyocardial cooling device of claim 96 wherein the inflatable bladder hasa curvature in the deployed state selected to conform to an exteriorsurface of the heart.
 105. The myocardial cooling device of claim 98wherein the inflatable bladder is configured to twist into a helicalconfiguration when contained within the sheath in the undeployed state.106. A surgical retraction device comprising: a shaft having a proximalend and a distal end; a contact surface adjacent said distal end foratraumatically contacting living tissue within a body cavity; and ameans for applying a vacuum at said contact surface.
 107. The surgicalretraction device of claim 106 wherein said means for applying a vacuumat said contact surface comprises a passage from said proximal end tosaid distal end of said shaft, said passage being in fluid communicationwith said contact surface.
 108. The surgical retraction device of claim106 wherein said contact surface further comprises a friction-increasingsurface.
 109. The surgical retraction device of claim 106 wherein saidcontact surface is flexibly mounted to said distal end of said shaft.110. The surgical retraction device of claim 106 wherein said contactsurface is mounted at an angle of approximately 45 degrees to alongitudinal axis of said shaft.
 111. The surgical retraction device ofclaim 108 wherein said friction-increasing surface comprises amultiplicity of bumps extending from said contact surface.
 112. Thesurgical retraction device of claim 106 wherein said contact surface isconcave.
 113. The surgical retraction device of claim 110 wherein saidcontact surface is disposed on a distal side of a cup-shaped memberattached to said distal end of said shaft.
 114. The surgical retractiondevice of claim 111 wherein said cup-shaped member is flexible.
 115. Thesurgical retraction device of claim 112 wherein said cup-shaped memberis sufficiently flexible to conform to a surface of a patient's heartwhen a vacuum is applied between said contact surface and the surface ofthe heart.
 116. The surgical retraction device of claim 113 wherein saidcontact surface further comprises a friction-increasing surface. 117.The surgical retraction device of claim 116 wherein saidfriction-increasing surface comprises a multiplicity of bumps extendingfrom said contact surface.
 118. The surgical retraction device of claim106 wherein said shaft and contact surface are configured to bepositioned through an access port in an intercostal space.
 119. Thesurgical retraction device of claim 118 wherein access port has adiameter of 12 mm.
 120. The surgical retraction device of claim 118wherein the contact surface is on a contact member attached to thedistal end of the shaft, contact surface being larger than the accessport in an unstressed condition, the contact member being collapsible soas to be positionable through the access port.
 121. A surgicalretraction device for retracting a body structure within a body cavity,the body structure having a curved external surface, the surgicalretraction device comprising: a rigid shaft having a distal end and aproximal end, the shaft having a contact surface near the distal endwith a curvature selected to conform to the external surface of the bodystructure; and a textured, porous material attached to the contactsurface for frictionally engaging the body structure; wherein a distalportion of the shaft including the contact surface and porous materialmay be introduced into the body cavity through an access port with adiameter of at most about 12 mm.
 122. The surgical retraction device ofclaim 121 wherein the porous material comprises a fabric pad.
 123. Thesurgical retraction device of claim 121 wherein the porous materialcomprises surgical gauze.
 124. The surgical retraction device of claim121 wherein the porous material comprises a foam pad.
 125. The surgicalretraction device of claim 121 wherein the porous material is wrappedaround a distal portion of the shaft.
 126. The surgical retractiondevice of claim 121 wherein the contact surface comprises a lateralsurface of a distal portion of the shaft, the distal portion of theshaft having a diameter of less than about 10 mm.
 127. The surgicalretraction device of claim 121 wherein the porous material covers thedistal end of the shaft.
 128. The surgical retraction device of claim121 further comprising an aspiration lumen within the shaft extendingfrom the proximal end to at least the contact surface, and a pluralityof holes in the contact surface in communication with the lumen, wherebya vacuum may be applied through the aspiration lumen and the holes towithdraw fluids from the porous material.
 129. The surgical retractiondevice of claim 121 wherein at least a portion of the shaft is malleablesuch that the contact surface may be shaped into various curvatures.130. A surgical retraction device for retracting a body structure withina body cavity, the retractor comprising: a rigid shaft having a proximalend and a distal end: a guide means along the shaft; and a flexible bandextending through the guide means so as to be slidable with respect tothe shaft, the flexible band forming a loop at the distal end of theshaft and having a first end attached to the shaft and a second endextending to the proximal end of the shaft, whereby the size of the loopmay be enlarged or reduced by sliding the band relative to the shaft;wherein a distal portion of the shaft and the loop may be introducedthrough an access port with a diameter of at most 12 mm.
 131. Thesurgical retraction device of claim 130 wherein the band has arectangular cross-section.
 132. The surgical retraction device of claim130 wherein the band is metal.
 134. The surgical retraction device ofclaim 130 wherein the loop has a friction-increasing inner surface forengaging the body structure.
 135. The surgical retraction device ofclaim 134 wherein the friction increasing inner surface comprises aporous material attached to the band.
 136. The surgical retractiondevice of claim 130 wherein the loop is formed around an axis which isgenerally perpendicular to a longitudinal axis of the shaft.
 137. Thesurgical retraction device of claim 130 wherein the loop is formedaround an axis parallel to a longitudinal axis of the shaft.
 138. Thesurgical retraction device of claim 130 wherein the band is asuperelastic alloy.
 139. The surgical retraction device of claim 130wherein the band is a shape-memory alloy.
 140. The surgical retractiondevice of claim 130 further comprising a link pivotably coupled to thedistal end of the shaft, the first end of the band being attached to thelink.
 141. The surgical retraction device of claim 140 wherein the linkis jointed so as to have a proximal section and a distal sectionpivotably attached to the proximal section, the proximal section beingpivotably attached to the shaft, and the distal section being attachedto the first end of the band.
 142. The surgical retraction device ofclaim 130 wherein the guide means comprises a lumen in the shaft, theband being disposed slidably within the lumen.
 143. The surgicalretraction device of claim 130 further comprising actuation means at theproximal end of the shaft for sliding the band relative to the shaft.144. A surgical tunneling instrument for tunneling between adjacent bodystructures in a body cavity, the tunneling instrument comprising: ashaft having a distal end, a proximal end and a lumen therebetween; alinkage extending through the lumen; an articulating finger at the endof the shaft, the articulating finger comprising: a first proximalmember having a proximal end and a distal end opposite the proximal end,the proximal end being pivotably coupled to the shaft at a first pointand coupled to the linkage at a second point laterally offset from thefirst point; a second proximal member having a proximal end pivotablycoupled to the shaft and a distal end opposite the proximal end; and adistal member having a proximal end and a distal end opposite theproximal end, the distal end being configured for tunneling between thebody structures, and the proximal end being pivotably coupled to thedistal end of the first proximal member at a third point and pivotablycoupled to the distal end of the second proximal member at a fourthpoint laterally offset from the third point; and means at the proximalend of the shaft for moving the linkage relative to the shaft, wherebythe first proximal member pivots relative to the shaft about the firstpoint and the distal member pivots relative to the first proximal memberabout the third point.
 145. The tunneling instrument of claim 144further comprising means at the distal end of the distal member forgrasping a vascular structure.
 146. The tunneling instrument of claim145 wherein the grasping means comprises a hook.
 147. The tunnelinginstrument of claim 145 wherein the grasping means comprises a snare.148. The tunneling instrument of claim 145 wherein the grasping meanscomprises a pair of grasping jaws, at least one of said grasping jawsbeing movable with respect to the other.
 149. The tunneling instrumentof claim 145 wherein the first and second points are separated by afirst transverse distance, and the third and fourth points are separatedby a second transverse distance, the first and second transversedistances being less than about 10 mm.